PrecauLarge.PMD 02/26/2007
An automatic fire alarm system
–typically made up of
smoke detectors, heat detectors, manual pull stations,
audible warning devices, and a fire alarm control panel with
remote notification capability–can provide early warning of a
developing fire. Such a system, however, does not assure
protection against property damage or loss of life resulting
from a fire.
The Manufacturer recommends that smoke and/or heat
detectors be located throughout a protected premise follow-
ing the recommendations of the current edition of the
National Fire Protection Association Standard 72 (NFPA 72),
manufacturer's recommendations, State and local codes,
and the recommendations contained in the Guides for
Proper Use of System Smoke Detectors, which are made
available at no charge to all installing dealers. These docu-
ments can be found at
http:/www.systemsensor.com/html/
applicat.html
. A study by the Federal Emergency Manage-
ment Agency (an agency of the United States government)
indicated that smoke detectors may not go off in as many as
35% of all fires. While fire alarm
systems are designed to provide early warning against fire,
they do not guarantee warning or protection against fire. A
fire alarm system may not provide timely or adequate
warning, or simply may not function, for a variety of reasons:
Smoke detectors
may not sense fire where smoke cannot
reach the detectors such as in chimneys, in or behind walls,
on roofs, or on the other side of closed doors. Smoke
detectors also may not sense a fire on another level or floor
of a building. A second-floor detector, for example, may not
sense a first-floor or basement fire.
Particles of combustion or "smoke"
from a developing fire
may not reach the sensing chambers of smoke detectors
because:
• Barriers such as closed or partially closed doors, walls, or
chimneys may inhibit particle or smoke flow.
• Smoke particles may become "cold," stratify, and not
reach the ceiling or upper walls where detectors are
located.
• Smoke particles may be blown away from detectors by air
outlets.
• Smoke particles may be drawn into air returns before
reaching the detector.
The amount of "smoke" present may be insufficient to alarm
smoke detectors. Smoke detectors are designed to alarm
at various levels of smoke density. If such density levels are
not created by a developing fire at the location of detectors,
the detectors will not go into alarm.
Smoke detectors, even when working properly, have sens-
ing limitations. Detectors that have photoelectronic sensing
chambers tend to detect smoldering fires better than flam-
ing fires, which have little visible smoke. Detectors that have
ionizing-type sensing chambers tend to detect fast-flaming
fires better than smoldering fires. Because fires develop in
different ways and are often unpredictable in their growth,
neither type of detector is necessarily best and a given type
of detector may not provide adequate warning of a fire.
Smoke detectors cannot be expected to provide adequate
warning of fires caused by arson, children playing with
matches (especially in bedrooms), smoking in bed, and
violent explosions (caused by escaping gas, improper stor-
age of flammable materials, etc.).
Heat detectors do not sense particles of combustion and
alarm only when heat on their sensors increases at a
predetermined rate or reaches a predetermined level.
Rate-of-rise heat detectors may be subject to reduced
sensitivity over time. For this reason, the rate-of-rise
feature of each detector should be tested at least once
per year by a qualified fire protection specialist.
Heat
detectors are designed to protect property, not life.
IMPORTANT!
Smoke detectors
must be installed in the
same room as the control panel and in rooms used by
the system for the connection of alarm transmission
wiring, communications, signaling, and/or power.
If
detectors are not so located, a developing fire may
damage the alarm system, crippling its ability to report
a fire.
Audible warning devices
such as bells may not alert
people if these devices are located on the other side of
closed or partly open doors or are located on another
floor of a building. Any warning device may fail to alert
people with a disability or those who have recently con-
sumed drugs, alcohol or medication. Please note that:
• Strobes can, under certain circumstances, cause
seizures in people with conditions such as epilepsy.
• Studies have shown that certain people, even when
they hear a fire alarm signal, do not respond or com-
prehend the meaning of the signal. It is the property
owner's responsibility to conduct fire drills and other
training exercise to make people aware of fire alarm
signals and instruct them on the proper reaction to
alarm signals.
• In rare instances, the sounding of a warning device
can cause temporary or permanent hearing loss.
A fire alarm system
will not operate without any
electrical power. If AC power fails, the system will
operate from standby batteries only for a specified time
and only if the batteries have been properly maintained
and replaced regularly.
Equipment used in the system
may not be technically
compatible with the control. It is essential to use only
equipment listed for service with your control panel.
Telephone lines
needed to transmit alarm signals from
a premise to a central monitoring station may be out of
service or temporarily disabled. For added protection
against telephone line failure, backup radio transmis-
sion systems are recommended.
The most common cause
of fire alarm malfunction is
inadequate maintenance. To keep the entire fire alarm
system in excellent working order, ongoing maintenance
is required per the manufacturer's recommendations,
and UL and NFPA standards. At a minimum, the require-
ments of NFPA 72 shall be followed. Environments with
large amounts of dust, dirt or high air velocity require
more frequent maintenance. A maintenance agreement
should be arranged through the local manufacturer's
representative. Maintenance should be scheduled
monthly or as required by National and/or local fire codes
and should be performed by authorized professional fire
alarm installers only. Adequate written records of all
inspections should be kept.
While a fire alarm system may lower insurance
rates, it is not a substitute for fire insurance!
Fire Alarm System Limitations
